When to plant sweet potato in Washington

In Washington, typical last spring frost is April 1 and typical first fall frost is November 11. Typical last spring frost: April 1. Sweet potato in Washington is a good fit outdoors. The suitable growing window of 145 days covers the 85–140 days this plant usually needs.

Sweet potato

How to grow Sweet potato Washington climate Weekly temperatures and windows

Where are you growing?

Comfortable

Tight fit in greenhouse

Comfortable in a cold frame

Sweet potato in Washington is a good fit outdoors. The suitable growing window of 145 days covers the 85–140 days this plant usually needs.

When to plantApril 28 – June 22

Harvest: July 22 – November 5
Season vs crop: 145 grow days vs 85–140 needed
Typical frost (last spring – first fall): April 1 – November 11

Sweet potato in Washington is a good fit outdoors. The suitable growing window of 145 days covers the 85–140 days this plant usually needs.

Planting conditions

Suitable growing days in a row145

Days to harvest85–140 days from planting

No planting window is recorded for this place.

Too cold
Frost line

Blue fill is usually too cold for this plant. Dashed lines are typical last and first frost (35 seasons (1991–2025)). Adjust a week or two for your conditions.

Planting and growing across the year

Planting is the sow / plant-out window. Growing is daytime air versus this plant’s ideal (21 – 32 °C70 – 90 °F21 – 32 °C (70 – 90 °F)) and tolerable (16 – 35 °C61 – 95 °F16 – 35 °C (61 – 95 °F)) ranges.

Ideal / plantable
Tolerable
Too cold
Too hot
Outside window

Planting uses sow / plant-out rules; growing shows daytime air against this plant’s ideal and tolerable ranges.

Key dates

Typical last spring frostApril 1

Low-risk last spring frostApril 11

Typical first fall frostNovember 11

Low-risk first fall frostNovember 5

Frost-free days223

Earliest indoor seed startMarch 17

Latest indoor seed startMay 11

Transplant outdoorsApril 28 – June 22

Direct sow windownot recommended here

Suitable growing windowApril 28 – September 19 (145 days)

Expected harvestJuly 22 – November 5

How these dates are judged

Ideal conditions: Daytime air from 21 – 32 °C70 – 90 °F21 – 32 °C (70 – 90 °F).
Suitable conditions: Daytime air from 16 – 35 °C61 – 95 °F16 – 35 °C (61 – 95 °F).
Last frost and first frost: Typical spring and fall frost dates for Washington, shown in the key dates.
Days to harvest: 85–140 days from planting, from typical days to harvest.
Sowing window: Dated sow and harvest bars use frost dates, soil minima, night limits, and last-sow count-back from typical crop timing. Air ratings on the weekly chart colour only weeks inside that same window — see weekly temperatures and windows.

Other plants for Washington

Calculated by Plan & Plant. Method. Data 35 seasons (1991–2025).

Frost and suitability dates are typical figures from climate statistics.

Based on 35 years (1991–2025) of ERA5-Land data from Open-Meteo, for an area of about 10 km. Typical dates, not a guarantee.

Dates for Washington use ERA5-Land cell 38.91, -77.04. How we calculated this · Algorithm 2026-10-season-10.

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